20
$\begingroup$

I live in Essex, England (51.7678° N, 0.0878° E). On 25 July 2019 (hottest day ever in the UK, btw), 06:43 BST, I took this smartphone photo of the Sun. Is that white dot just below and left of the Sun the planet Mars? I've checked with my SkySafari app and it looks like it could be Mars, but I'm just surprised that my relatively cheap phone could take a picture of the planet. Although the photo is quite dark, it was a bright day. Thank you.

enter image description here

$\endgroup$
44
$\begingroup$

That is a camera artefact caused by the bright sunlight reflecting within the lens on your phone. It’s more pronounced than on a large camera because of the small lens size. This is a secondary image of the sun, as the brightness of the source allows for the reflection to be still intense enough to be detected.

Here is a photo I took with the same artefact. It appears for me as a cyan dot with a magenta outside, but other photos I’ve taken have one with the same colour as the sun.

Notice if you zoom in on yours, there’s a halo around the artefact as well.

Also notice that the artefact is directly below the sun in my image, whereas in yours it’s slightly to the left. However, this is because in your image the sun is slightly to the right, and hitting the lens at an angle.

As uhoh says, you can see that the sun is the same distance from the centre of the image as the lens flare (or very close to):

It should be possible to take a photo with the artefact wherever you want, by re-angling the phone - including inside the sun, where it will be drowned out.

I actually took my phone into an Apple Store to find out what this was, where they explained the lens flair effect. Unfortunately I don’t have a source for this, as it was in person. Hopefully the above is convincing enough.

$\endgroup$
  • 3
    $\begingroup$ I actually took my phone to Apple to find out what this was how much did it cost? $\endgroup$ – wha7ever - Reinstate Monica Aug 7 at 19:51
  • 2
    $\begingroup$ @whatever nothing $\endgroup$ – Tim Aug 7 at 19:53
  • 1
    $\begingroup$ Actually, your "Mars dot" is distinctly to the left, too -- look at where the bright rays converge. $\endgroup$ – David Richerby Aug 7 at 21:11
  • $\begingroup$ @DavidRicherby yes, you’re right it is slightly to the left, just less noticeably. I think it would still match up as equal distances from the centre $\endgroup$ – Tim Aug 7 at 23:09
  • 1
    $\begingroup$ +1 for the axis on the final image showing the relation to the sun, which helps explain what lens flare is (a reflection). $\endgroup$ – brichins Aug 7 at 23:39
15
$\begingroup$

Stellarium shows Mars close to the Sun and just above the horizon at that date and time. Unfortunately, Mars is only 2° above the horizon (and also on the other side of the Sun to the Earth), so it is very unlikely to be visible against the Sun's glare and through atmospheric haze (atmospheric effects are disabled in the Stellarium image below). Still, it's a nice photograph, but the light on the horizon is probably something much closer to home.

Stellarium image showing Mars, Mercury and Venus close to the Sun

Stellarium

Note that local time is shown, not UTC.

$\endgroup$
  • $\begingroup$ Compare Mars's magnitude to Castor and Pollux, similar separations from the Sun and in a darker part of the sky. $\endgroup$ – Mike G Aug 6 at 18:23
  • 1
    $\begingroup$ @MikeG Yeah! I did wonder about that. Stellarium shows Mars as being just 2° above the horizon, so the answer is almost certainly "no". $\endgroup$ – Mick Aug 6 at 18:31
11
$\begingroup$

A quick check shows that the spot is diametrically opposite the Sun, which although not at all conclusive, adds credence to it likely being lens flare.

enter image description here

import numpy as np
import matplotlib.pyplot as plt

img = plt.imread('sun flare.png')[:, :, :3].copy()

s0, s1 = img.shape[:2]
X,  Y  = np.meshgrid(np.arange(s1), np.arange(s0))

x0, y0 = 163, 154
x1, y1 = s1 - x0, s0 - y0

R0     = np.sqrt((X-x0)**2 + (Y-y0)**2)
R1     = np.sqrt((X-x1)**2 + (Y-y1)**2)

red    = (6 <= R0)*(R0 <= 9) + (6 <= R1)*(R1 <= 9)

img[red] = np.array([1, 0, 0])

if True:
    plt.figure()
    plt.imshow(img)
    plt.show()
$\endgroup$
  • $\begingroup$ Good call! That's it. $\endgroup$ – Mick Aug 7 at 21:02
  • 2
    $\begingroup$ "Diametrically opposite" means at the opposite end of a diameter of some circle. What circle are you talking about? $\endgroup$ – David Richerby Aug 7 at 21:12
  • 2
    $\begingroup$ @DavidRicherby the circular rectangle is the 2D analog of the spherical cow. $\endgroup$ – uhoh Aug 7 at 21:40
  • 3
    $\begingroup$ @DavidRicherby the circle centred on the centre of the image $\endgroup$ – Tim Aug 8 at 6:49
  • 2
    $\begingroup$ @MobyDisk yes, but not every pixel is opposite every other pixel on the same circle. See: this image. The red circle is centred on the centre of the image, and goes through both the centre of the sun (the blue circle) and the flare. My answer above may clear this up further for you? $\endgroup$ – Tim Aug 8 at 14:09
6
$\begingroup$

Given your location, the bright light could be the sun's reflection off an aircraft coming into/leaving London Stansted airport.

$\endgroup$
  • $\begingroup$ Disappointing, but very likely. $\endgroup$ – Peter Aug 6 at 19:47
  • $\begingroup$ Seems like a strange location for the airplane to be (it’s rare to see them so close to the horizon, and most of Essex isn’t near Stansted). It’s also unlikely for the light to reflect off towards the camera considering the sun is behind the theoretical airplane. $\endgroup$ – Tim Aug 7 at 10:59
  • $\begingroup$ @Tim not if you are near the flightpath. I see flights coming into London City Airport that low every day. $\endgroup$ – Dr Chuck Aug 7 at 11:50
  • $\begingroup$ @DrChuck sorry I should have clarified: it’s rare to see them that low if you’re not near the flightpath - and in this photo they’re a long way away from the flight path. It’s possible for it to be an airplane, but seems very unlikely. $\endgroup$ – Tim Aug 7 at 11:51
3
$\begingroup$

The only planet I have seen in broad daylight, and on a much brighter day than this with the sun much higher in he sky, is Venus. It was quite clearly visible, one didn't need unusually good vision to see it. I tried to pretend it was a flying saucer, but I don't think I fooled anyone. I don't know where Venus was on the day this photo was taken, but if the smaller bright spot we can see is a planet, it can only be Venus. Venus shows phases like the moon, and at closest approach comes within 26 million miles of Earth, closer than any other planet. It also has a high albedo because of its clouds.

$\endgroup$
  • 2
    $\begingroup$ Venus is close to the Sun, but higher in the ecliptic (see my Stellarium screenshot). The object in the OP's picture seems to be in exactly the right place to be Mars (if my Stellarium setup is correct), but I don't see how it could be visible so low in the sky when it is almost in conjunction. Mars hasn't moved much, so it'll be in the same place, at the same time, tomorrow. I might go out and have a look if the weather's good, but I don't have a clear view of the eastern horizon. I shall need to drive to a fairly high spot. Venus will be 2° west of the Sun tomorrow. $\endgroup$ – Mick Aug 6 at 21:29
  • 1
    $\begingroup$ Strange things can happen n the sky, especially under unusual atmospheric conditions. You might find it hard to believe that I've seen sunspots quite easily with the naked eye, but I have. $\endgroup$ – Michael Walsby Aug 6 at 21:33
  • 1
    $\begingroup$ PS You can't see Mars by day, it isn't bright enough. If it wasn't Venus, it couldn't have been a planet. $\endgroup$ – Michael Walsby Aug 6 at 21:39
  • $\begingroup$ Not much point getting out of bed, then? $\endgroup$ – Mick Aug 6 at 22:48
  • 1
    $\begingroup$ "You might find it hard to believe that I've seen sunspots quite easily with the naked eye..." People who look directly at the Sun will often see spots, on the Sun, on their breakfast, in the middle of the road... $\endgroup$ – uhoh Aug 11 at 23:32
0
$\begingroup$

As an addition to the excellent answer by Tim, one can exploit this reflection to do some interesting solar imagery. Here's a picture I took with my phone during the (where I was, partial) eclipse back in August of 2017 (cropped to be more visible). The sun (as expected) is quite bright, and washes out everything - no amount of lowering ISO / increasing shutter would help on a mobile phone's sensor, but the internal reflection attenuated the light enough so that the shape is visible.

Bright sun with lens flare in shape of the eclipse (cropped)

$\endgroup$
  • 1
    $\begingroup$ This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post. - From Review $\endgroup$ – Jan Doggen Aug 9 at 19:24
  • 1
    $\begingroup$ @JanDoggen: I would argue it does help answer the question "Is that white dot just below and left of the Sun the planet Mars?" - by giving a more obvious example as to the fact that it's actually reflections of the sun on the internal optics of the lens. $\endgroup$ – Tyzoid Aug 12 at 14:34

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.